The End of the Cretaceous: Sharp Boundary or Gradual Transition?

Science  16 Mar 1984:
Vol. 223, Issue 4641, pp. 1183-1186
DOI: 10.1126/science.223.4641.1183


Evidence indicates that the Cretaceous-Tertiary boundary is very sharp, and, within the limits of resolution, it is apparently synchronous at the various boundary localities. Arguments to the contrary, particularly those of Officer and Darke, are shown to invalid.